Florida researchers promise plastic circuits

Research into how charge is stored in polymer molecule chains could pave the way for "molecular wires" that would replace silicon circuitry. Scientists at the US Department of Energy's Brookhaven National Laboratory and the University of Florida say the results could have particular application in the solar energy industry.

Unlike their silicon counterparts, the molecules need a helping hand to move electrons around, so the team used the Brookhaven's Laser-Electron Accelerator Facility (LEAF), to generate high-energy electrons for their experiment.

The researchers, led by chemist John Miller, first immersed their molecular wire in an organic fluid and then fired the high-energy electrons through the fluid. The electrons cause the wires to take on an extra positive or negative charge. The scientists can track how the charge diffuses across the wire, helping them to identify good conductors.

In conventional solar panels the energy from the sun is excites electrons in a semiconducting material such as silicon, creating the current flow. Replacing the silicon with polymer nanowires would make the solar cell much lighter, and eventually cheaper.

The so-called plastic solar cells can be made much bigger and are also more flexible, making them more versatile. Normal solar panels are rigid, expensive and their size is constrained by manufacturing techniques.

However, there is still work to do. At the moment it takes a lot of energy for an electron to move from one molecular wire to another. Miller says that the next step is to find a way to eliminate this barrier. But first they need a better understanding of which polymer materials make the best conductors. ®